Are criminal justice reforms and immigration policy at odds?

The Department of Justice recently announced a decision to release 6,000 people from federal prison. As part of that announcement, agency officials noted that 1/3 of the people released are immigrants who will be quickly deported.

There is a clear and troubling pattern where policy reforms in the criminal justice system do not extend to immigrants in the criminal justice or immigration enforcement systems. The glaring question is: why not?